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    SubjectRe: Thread-private mappings and graphics (was Re: Per-Processor Data Page)
    On Thu, Dec 16, 1999 at 04:40:09PM -0800, Linus Torvalds wrote:

    > Note that historically atomic locks have been EXPENSIVE. I think that was
    > true on MIPS too, even with the load-locked thing, just because with the
    > weak cache coherency the thing was initially done on the _bus_, not inside
    > the CPU. But happily that time is long gone, and it's not coming back.

    ll/sc instructions on MIPS are as expensive as normal loads / stores.

    (The pre-ll/sc thing SGI used in their R3000 based SMPs was horribly
    expensive, special purpose hardware that was of course different from other
    MIPS vendors' solutions and apparently at times needed *miliseconds* to do
    an atomic operation old SGIers told me ...)

    Ralf

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